Furnace construction for fluid fuel fired air-heating furnaces



March 2E, 1950 H. J. GATES 2,501,041

FURNACE CONSTRUCTION FoR FLUID FUEL. FIRRD AIR HEATING FURNAcFs Filed Jan. 16, 1947* Q /l l,\\\ N5 /l/ or Q w N n INVENTOR.

www)

Patented Mar. 2l, 1950 rlifgrg UNITED STATES PATENT OFFICE FURNACE CONSTRUCTION FOR FLUID FUEL FIRED AIReHEATIN G FURNACES Harold J. Gates, Coldwater, Mich. Application January 16, 1947,`seria1Nc. 722,403

9 Claims. (C1. 12s-116) 1 2 This invention relates to improvements in upper portion of the heating chamber I through furnace construction. a small bleed ue I3 which is considerably The principal objects of this invention are: smaller in cross sectional area than the area of First, to increase the efficiency of the heat eX- the down draft flue 8. change surfaces of a furnace of the oil burner 5 A clean-out door I4 is provided at the front of type. the heating chamber and a second clean-out door Second, to provide a furnace having a downi5 is provided at the front of the heat exchanger. wardly directed reverse flow of the products of The parts of the furnace are supported upon vercombustion for increasing the efficiency of the tical legs IB which are provided With lower cross heat exchange surfaces of the furnace. members I1 supporting the heat exchanger and Third, to provide a furnace having a main an upper cross member I8 supporting the rear downiiow passage for the majority of products end of the heating chamber in vertically spaced of combustion and an auxiliary bleed passage for relationship with the heat exchanger. insuring circulation of the products of combustion The front cover plate 'I defines a central apere through the heat exchange passages. ture I9 around the side of which is secured a Fourth, t0 DTOVde 2f fuinaCe 01c the Oil 01 gS burner tube 20 which projects into the heating burner type with nues which direct the products chamber. The inner end of the burner tube is of combustion downwardly to a heat exchange secured to a semi-cylindrical combustion chamchamber spaced below the combustion chamber of ber support 2| which is of Sughi-,1y Smaller d the furnace. 2o ameter than the diameter of the opening 6 in Fifth, t0 provide a furnace in which the prodthe front Wall 5 of the furnace so that the comucts of combustion iiow counter to the oW 0f bustion chamber support may be inserted into the air around the furnace whereby an ideal heet heating chamber through the opening t. Vertical eXChange relatiOnShp iS Obtained between the plates 22 secured to the lower wall 4 of the heathot gases in the furnace and the air being warmed ing chamber Support the Combustion Chamber around the outside of the furnace. support within the heating chamber. The com- Other Objects and advantages pertaining to the bustion chamber support 2l carries a cylindrical details and economies of the invention will be combustion chamber 23 of refractory material apparent from the following description and which is open at both ends and which is held in claims. 3U place on the support 2| by a plurality of straps The drawings, of which there is one sheet, illus- 24. trate a preferred form of my furnace. A sight tube 25 extends between the forward Fig. 1 is a front elevational View partially end of the combustion chamber support and an bYOkeIl Way in CTOSS Section 0f my fumae With aperture near the top of the cover plate 'l and is a hot air jacket positioned around the furnace provided with a nreproof sight window 26 so that and conventionally illustrated by dotted lines. the type and condition of the flame within the Fig- 2 iS a longitudine] CIOSS SeCtOnal VeW combustion chamber may be observed from outalong the broken line 2-2 in Fig. 1. D side the furnace.

As illustrated in the drawings, my furnace is The burner tube 2D is arranged to receive the provided with an upper heating chamber I deend of a gun-type oil burner illustrated convenned by top and side walls 2, rear wall 3, bottom tionally at 21 which directs a mixture of atomized wall 4 and front wall 5. The front wall defines fuel oil and air into the combustion chamber a large circular aperture 6 which is partially where it is ignited. Secondary air for the comclosed by the front plate 'I and the bottom wall 4 bustion chamber enters through the burner tube is terminated short of the front wall thus forming 20 and around the barrel of the burner. While an opening to a down draft ue 8 (see Fig. 2) an oil burner is illustrated, certain types of preswhich Opens into a heat exchanger 9. The heat sure gas burners will operate equally well in the exchanger' iS PTOVided With a plurality 0f longfurnace. Since my invention is concerned pritlldnally extending hOt gas filles U WhCh are marily with the heat exchange properties and the spaced laterally from each other and connected circulation of the products of combustion within at their rear ends to a riser I I extending upwardly the furnace the particular type of burner has not in spaced relationship behind the rear wall 3. been illustrated in greater detail.

The upper end of the riser I I is provided with a For the most efficient transfer and distribution rearwardly extending smoke flue I2 and the of heat the furnace will be provided with a suitupper end of the riser communicates with the able hot air jacket illustrated by dotted lines at 28 in Fig. 1 and having hot air collars 29 and a cold air return boot 30. The hot air jacket is of conventional construction well known to furnace manufacturers and so is not illustrated in detail.

In operation the fuel injected by the oil burner 21 will burn first in the refractory combustion chamber 23 and the products of combustion will pass from there into the heating chamber I. When the furnace is first started the natural tendency of the hot products of combustion to rise will cause part of the hot gases to pass through the small bleed flue I3 directly to the upper end of the riser II and smoke pipe I2. The passage of these Igases through the top of the riser and the smoke pipe will induce an upward draft through the riser II prior to the air in the riser becoming heated to cause its own natural draft. The induced draft in the riser will act through the heat exchanger to draw some of the products of combustion in the heating chamber downwardly through the down draft ue 8 and through the heat exchanger. As the heat exchanger and riser fill with hot gases a natural draft will rapidly be set up through them of much larger magnitude than the induced draft. Since the area of the bleed flue is relatively small compared to the total volume of hot gases being introduced into the heating chamber, the main portion of the hot gases will be forced forwardly through the heating chamber and downwardly along the front wall around the burner tube 2D and through the down draft flue 8 to the heat exchanger 9 where the natural draft in the riser II will be effective to draw them through the ues I0. Once the circulation through the heating chamber and heat exchanger Ill is set up the majority of the products of combustion will continue to pass through the heat exchanger and the riser to the smoke pipe I2 rather than through the bleed flue I3.

With the hot gases in the furnace circulating as just described, the gases will naturally be hottest along the upper portion of the heating chamber I and will be cooled slightly as they pass downwardly into the heat exchanger Ill. Thus the gases in the heat exchanger will be at a lower temperature than those in the top of the heating chamber. Cold air entering the furnace jacket through the boot will thus come rst in contact with the relatively lower temperature of the heat exchanger. However, due to the still lower temperatureof the air, temperature difference between the incoming air and the gases in the heat exchanger is sufficient to insure rapid and efficient transfer of heat to the incoming air. As the incoming air becomes heated and rises through the heat exchanger it will come in contact with the outside of the heating chamber I and rise along the sides thereof toward the outlet pipes 29. As the temperature of the air being heated increases the air comes in contact with increasingly hot portions of the heating chamber thus insuring a high temperature differential between the air being heated and the hot gases within the heating chamber. The counter-flow of the hot gases and air being heated thus set up insures a maximum of transfer of heat from the hot gases to the air entirely through the furnace. Thus a minimum amount of heat exchange area or furnace wall surface will provide a maximum amount of heat transfer to the air around the furnace and for any given capacity of burner the size of the furnace may be reduced below that required by a furnace having conventional circulation of the hot gases therein.

It will be noted that the hot gases descending along the front of the heater chamber will pass around the burner pipe 20 thus heating the secondary air which enters the combustion chamber between the burner and the burner tube 20. This heating of the secondary air renders the operation of the burner more efficient since less of the heat during combustion is expended in heating the air thus producing a hotter flame within the refractory combustion chamber.

I have shown a generally rectangular furnace and combustion chamber and have not attempted to illustrate other possible shapes of heating chambers and heat exchangers but obviously the principles of operation illustrated could be applied to furnaces of various shapes and sizes. It is felt that this disclosure will permit others to reproduce furnaces operating by my system with such Variations and modifications as may be desired without further description.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A hot air furnace comprising walls forming a heater chamber with a front wall dening a circular aperture and a lower wall dening an opening near the front thereof, a heat exchanger having a plurality of horizontally extending flue passages and spaced below said heater chamber and communicating therewith through said opening in said bottom wall, a riser communicating with the opposite ends of said flues from said heater chamber and extending upwardly in spaced relation behind said heater chamber, a smoke pipe opening into the upper end of said riser, a bleed flue extending between the tops of said heater chamber and riser, a circular front plate for closing said front aperture and defining a smaller central aperture, a cylindrical burner pipe secured to the edge of said smaller aperture, a semi-cylindrical support having an annular end plate of larger diameter than said burner pipe secured to the inner end of said burner pipe, said lower wall having a plate eX- tending upwardly therefrom to support the underside of said semi-cylindrical support in spaced relationship with the Walls of said heater chamber, a cylindrical tube of refractory material forming a combustion chamber positioned in said semi-cylindrical support and open at its inner end, a gun-type oil burner projecting through said burner pipe into said combustion chamber, and a sight tube extending between said annular plate and said front plate, said bleed flue ibeing of smaller cross sectional area than said riser.

2. A hot air furnace comprising walls forming heater chamber with a front wall defining a circular aperture and a lower wall defining an opening near the front thereof, a heat exchanger having a plurality of horizontally extending flue passages and spaced below said heater chamber and communicating therewith through said opening in said bottom wall, a riser communicating with the opposite ends of said flues from said heater chamber and extending upwardly in spaced relation behind said heater chamber, a

`smoke pipe opening into the upper end of said riser, a bleed flue extending between the tops of said heater chamber and riser, a circular front plate for closing said front aperture and defining a smaller central aperture, a cylindrical burner pipe secured around said smaller aperture, a

semi-cylindrical support having an annular end plate of larger diameter than said burner pipe secured to the inner end of said burner pipe, said lower wall having a plate extending upwardly therefrom to support the underside of said semicylindrical support in spaced relationship with thewalls of said heater chamber, a cylindrical tube of refractory material forming a combustion chamber positioned in said semi-cylindrical support and open at its inner end, a gun-type oil burner projecting through said burner pipe into said combustion chamber, and a sight tube extending between said annular plate vand said front plate, said bleed ue beingr of smaller capacity than that required to carry off the products of combustion of said burner.

3. A hot yair furnace comprising walls forming a heating chamber having a front wall defining an aperture and a lower wall having an opening near the front thereof, a down draft flue connected to said heating chamber around said opening, a heat exchanger having a plurality of horizontal flues communicating with the bottom of said down draft flue and extending in spaced relationship under said heating chamber, a riser connected with the ends of said heat exchanger nues and extending upwardly in spaced relationship with the back of said heating chamber, a smoke flue opening from the upper end of said riser, a bleed flue communicating through the rear wall of said heating chamber between th;` upper portions of said heating chamber and said riser, said bleed flue having a smaller cross sectional area than said down draft flue, a cover plate arranged to close the aperture in said heating chamber, a burner pipe projecting inwardly from said plate and opening therethrough, a semi-cylindrical combustion chamber support having an annular end plate secured to the inner end of said burner pipe, a cylindrical tube of refractory material forming a combustion chamber position on said combustion chamber support and movable with said support into said heating chamber through said aperture, a sight tube opening between said combustion chamber and the outside of said cover plate and having a transparent cover on the outer end thereof, a support plate for supporting the bottom of said combustion chamber support from the lower wall of said heating chamber, and a gun-type oil burner having its discharge end projecting into said Yburner pipe.

4. A hot air furnace comprising walls forming a heating chamber having a front wall defining an aperture and a lower wall having an opening near the front thereof, a down draft flue connected to said heating chamber around said opening, a heat exchanger having a plurality of ues communicating with said down draft ilue and extending under said heating chamber, a riser connected with the ends of said heat exchanger iiues and extending upwardly in spaced relationship with said heating chamber, a smoke flue opening from the upper end of said riser, a bleed flue communicating between the upper portions of said heating chamber and said riser, said bleed nue having a smaller cross sectional area than said down draft flue, a cover plate arranged to close the aperture in said heating chamber, a burner pipe projecting inwardly from said plate and opening therethrough, a combustion chamber support having an annular end plate secured to the inner end of said burner pipe, a tube of refractory material forming a combustion chamber positioned in said combustion chamber support and movable into said heating chamber through said aperture, a sight tubeope'ning between Said combustion chamber and the outside of said cover plate and having a transparent cover on the outer end thereof, a support plate for supporting the bottom of said combustion chamber support from' the front thereof, a down draft flue connectedy around said opening, a heat exchanger having a plurality of flues communicating with said down draft flue and extending under said heating chamber, a riser connected with the ends ofV said heat exchanger flues and extending upwardly in spaced relationship with said heating chamber, a smoke flue opening from the upper endY of said riser, a bleed iiue communicating between the upper portions of said heating chamber and said riser, said bleed flue having a smaller cross,

sectional area than said down draft flue, a cover plate arranged to close the aperture in said heating chamber, a burner pipe projecting inwardlyr from said plate and opening therethrough, walls forming a combustion chamber secured to the inner end of said burner pipe and spaced from the front wall of said heating chamber, a sight tube opening between said combustion chamber and the outside of said cover plate and having a transparent cover on the outer end thereof, a support platey for supporting the bottom of said combustion chamber from the lower wall of said heating chamber, and a pressure type burner having its discharge end projecting into said burner pipe.

6. A hot air furnace comprising walls forming a heating chamber with a front wall defining an aperture and a lower wall having an opening along the front thereof, a down draft flue connected around said opening, a heat exchanger having a flue communicating with said down draft iiue and extending under said heating chamber, a riser connected with the end of said iiue and extending upwardly in spaced relationship with said heating chamber, a smoke iiue opening from the upper end of said riser, a bleed flue communicating between the upper portions of said heating chamber and said riser, said bleed flue having a smaller cross sectional area than said down draft flue, a cover plate arranged to close the aperture in said heating chamber, a burner pipe projecting inwardly from said plate and opening therethrough, said burner pipe projecting over said downdraft flue, walls forming a combustion chamber secured to the inner end of said burner pipe and movable into said heating chamber through said aperture by movement of said cover plate, and a pressure type burner having its discharge end projecting into said burner pipe.

7. A hot air furnace comprising generally rectilinear front, back, bottom and side walls defining a heating chamber, said front wall defining an aperture, said bottom wall terminating short of said front wall and defining an opening therewith, a heat exchanger positioned below said heating chamber, a flue connecting said opening with said heat exchanger, a riser connected tothe discharge side of said heat exchanger and extending upwardly in spaced relationship with the back of said heating chamber, a constantly open bleed ue communicating between the upper ends of said heating chamber and riser above the level of said aperture and having a smaller flue area than said heat exchangeniasmokeue opening` from said riser 4opposite saidv bleed flue, a cover plate for closing said aperture in said front plate and defining a burner aperture,.,a,burner tube projecting inwardly from said .burner aperture and over said opening, refractory means Vforming a combustion chamber carried onthe inner end of said burner tube and.communicatingtherewith, said means being removable from vsaid heating chamber through said aperture by movement of said cover plate, and a support for the bottom of said means carried on said bottom wall.

8. A hot air furnace comprising walls defining a. heating chamber, the front wall of said chamber defining an aperture, the bottom wall of said chamber defining a flue opening adjacent to Said front wall, a cover for closing said aperture, a burner tube opening through said cover and projecting inwardly of said chamber, a support on the inner end of said tube, and refractory means on said support defining a combustion chamber opening to said tube and toward the rear of said heating chamber, said combustion chamber being spaced from said front and bottom walls of said heating chamber whereby hot gases from said combustion chamber may contact said front and bottom wall, said combustion chamber being larger than said burner tube and smaller than said aperture in said front plate.

9. A hot air furnace comprising walls defining a heating chamber, the front wall of said chamber defining an aperture, the bottom wall of said chamber defining a ilue opening adjacent to said front iwall; a cover.: for closing` ,said4v aperture, a fburner tube opening through said cover and projecting inwardly of. said chamber, a support on the inner end of said tube, refractory means on said support defining a combustion chamber opening to said tube and toward the rear of said heating chamber, said combustion chamber being spaced from said front and bottom walls of said heating chamber whereby hot gases from said combustion chamber may contact said front and bottom wall, said combustion chamber being larger than said burner tube and smaller than said aperture in said front plate and a n projecting upwardly from said bottom wall in supporting engagement with said support.

l Y HAROLD J. GATES.

REFERENCES CITED The following references are of record in the Henderson et al. May 15, 1945 

